Skip copying CIDs to SSL transforms until CID feature is complete

This commit temporarily comments the copying of the negotiated CIDs
into the established ::mbedtls_ssl_transform in mbedtls_ssl_derive_keys()
until the CID feature has been fully implemented.

While mbedtls_ssl_decrypt_buf() and mbedtls_ssl_encrypt_buf() do
support CID-based record protection by now and can be unit tested,
the following two changes in the rest of the stack are still missing
before CID-based record protection can be integrated:
- Parsing of CIDs in incoming records.
- Allowing the new CID record content type for incoming records.
- Dealing with a change of record content type during record
  decryption.

Further, since mbedtls_ssl_get_peer_cid() judges the use of CIDs by
the CID fields in the currently transforms, this change also requires
temporarily disabling some grepping for ssl_client2 / ssl_server2
debug output in ssl-opt.sh.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index af8bfde..c558a84 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -956,11 +956,14 @@
     if( ssl->handshake->cid_in_use == MBEDTLS_SSL_CID_ENABLED )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "Copy CIDs into SSL transform" ) );
-        transform->in_cid_len = ssl->own_cid_len;
-        transform->out_cid_len = ssl->handshake->peer_cid_len;
-        memcpy( transform->in_cid, ssl->own_cid, ssl->own_cid_len );
-        memcpy( transform->out_cid, ssl->handshake->peer_cid,
-                ssl->handshake->peer_cid_len );
+
+        /* Uncomment this once CID-parsing and support for a change
+         * record content type during record decryption are added. */
+        /* transform->in_cid_len = ssl->own_cid_len; */
+        /* transform->out_cid_len = ssl->handshake->peer_cid_len; */
+        /* memcpy( transform->in_cid, ssl->own_cid, ssl->own_cid_len ); */
+        /* memcpy( transform->out_cid, ssl->handshake->peer_cid, */
+        /*         ssl->handshake->peer_cid_len ); */
 
         MBEDTLS_SSL_DEBUG_BUF( 3, "Outgoing CID", transform->out_cid,
                                transform->out_cid_len );